Image processing device having functions for detecting specified images

ABSTRACT

With a photocopier which stores original images read with a scanner in page memory, and prints later, in the event that judgment is made by a specified original judging unit that a specified original image is contained in an original document scanned for printing, the image signals stored in the memory are substituted with substitution image signals stored beforehand, and then output to a printer unit.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an image processing devicehaving forgery preventing function for preventing unauthorizedreproduction of specified images regarding which duplication isforbidden, such as paper currency.

[0003] 2. Description of the Related Art

[0004] A so-called color photocopier such as shown in FIG. 1 is known asa system for digital reading images of color originals and generatingduplicate images.

[0005] In FIG. 1, an image scanner unit 1001 reads the original imagesand performs digital signal processing. Also, a printer unit 1002performs full-color printer output of an image corresponding to theoriginal image read by the image scanner 1001 on recording paper.

[0006] At the image scanner 1001, an original 1004 placed between apressing plate 1000 having an original pressing face which has beensubjected to mirror finishing and an original table glass 1003 isirradiated by the light of a lamp 1005. The reflected light from theoriginal 1004 is guided to mirrors 1006, 1007, and 1008, and forms animage on a 3-line solid-state imaging device (hereafter referred to as“CCD”) 1010 by a lens 1009. The three image signals red (R), green (G),and blue (B), output from the CCD 1010 are sent to a signal processingunit 1011. Here, the lamp 1005 and mirror 1006 are mechanically moved ata speed V in a perpendicular direction as to the electric scanning (mainscanning) direction of the CCD 1010, and the mirrors 1007 and 1008 at aspeed V/2, thereby scanning the entire surface of the original 1004(sub-scanning). The image on the original 1004 is read at a resolutionof 400 dpi in both main scanning and sub-scanning.

[0007] The signal processing unit 1011 electrically processes the inputimage signals so as to divide into the components of magenta (M), cyan(C), yellow (Y), and black (K), and sends CMYK image signals to theprinter unit 1002. One color component of M, C, Y, and K, is sent to theprinter unit 1002 for each time the original is scanned by the imagescanner 1001, so one printout is completed by the original being scanneda total of four times.

[0008] At the printer unit 1002, the C, M, Y, or K image signals inputfrom the image scanner unit 1001 are sent to a laser driver 1012. Thelaser driver 1012 performs modulation driving of a semiconductor laserdevice 1013 according to the input image signals. The laser beam outputfrom the semiconductor laser device 1013 scans over a photosensitivedrum 1017 via a polygon mirror 1014, f-θ lens 1015, and mirror 1016, soas to form a 400 dpi electrostatic latent image on the photosensitivedrum 1017 for the main scan and sub-scan.

[0009] A rotating developer 1018 is configured of the magenta developingunit 1019, a cyan developing unit 1020, a yellow developing unit 1021,and a black developing unit 1022, with the four developing unitsalternately coming into contact with the photosensitive drum 1017,thereby developing the electrostatic latent image formed on thephotosensitive drum 1017 with toner. A transfer drum 1023 has recordingpaper, supplied from recording sheet cassettes 1024 or 1025, wrappedthereupon, and the toner image formed on the photosensitive drum 1017 istransferred onto the recording paper.

[0010] Thus, the four color toner images of M, C, Y, and K, aresequentially transferred on the recording paper, following which therecording paper passes through a fixing unit 1026, and the recordingpaper with toner fixed thereupon is discharged out of the apparatus.

[0011] As described in U.S. Pat. Nos. 5,321,470, 5,216,724, 5,633,952,5,430,525, 5,227,871, etc., with a color photocopier of such aconfiguration, the signal processing unit 1011 is arranged such thatimage signals representing an original image are analyzed, judgement ismade regarding whether or not there are specified original imagesregarding which duplication is forbidden, such as paper currency(hereafter referred to as “specified original judging”), and in theevent that judgement is made that a specified original image existstherein, the image output from the printer unit 1002 is filled in suchthat correct duplication result cannot be obtained, by substituting theimage signals sent to the printer unit 1002 with, for example, apredetermined value that is not dependent on the original image, or thelike. As described above, the configuration shown in FIG. 1 reads theoriginal image four times repeatedly, so acts of forgery can beprevented before they occur, by, for example, performing the specifiedoriginal judging at the time of reading the first time, and formation ofthe M color component latent image, in parallel, so in the event thatjudgement is obtained that a specified original image does exist, thelaser driving signals (image signals) of the subsequent C, Y, and Kcolor components are substituted with a predetermined value, therebycoloring the entire output image practically black.

[0012] With the above-described color photocopier, there is basicallythe need for the image scanner unit 1001 which reads original images andthe printer unit 1002 which outputs photocopied images, to operatesynchronously. That is to say, the RGB image signals output from the CCD1010 are processed at the signal processing unit 1011 one pixel at atime and converted into CMYK image signals, sent to the printer unit1002 sequentially, and form an electrostatic latent image on thephotosensitive drum 1017. Image formation is performed for one of thecolor components M, C, Y, and K, the image formation process is repeatedfor each of the color component, and original image reading is performedfour times consecutively. Accordingly, the image output at the end canbe colored in so long as the specified original judgment is performed byat least the third scan of the four scans.

[0013] Also, with the above-described color photocopier configuration,the image scanner unit 1001 and the printer unit 1002 need to operate atthe same time. For example, in the event that the fixing unit 1026 is anormal thermal fixing type, and the heater is not sufficiently heated,the printer unit 1002 will go into standby, so photocopying and imagereading cannot be performed.

[0014] In the event of photocopying multiple copies of an original imagewith the configuration of the above-described color photocopier, thereis the need to read the image multiple times according to the multiplecopies to be output. Further, in the event that there are multipleoriginals, the originals need to each be read multiple times, so thetime required for photocopying color originals is great.

[0015] Now, there is a configuration wherein page memory for storing atleast one page worth of color image that has been read is provided inthe image scanner unit 1001, and the photocopy images output by readingout the image from the page memory four times repeatedly, therebyenabling multiple outputs with reading the image only one time. Withsuch a configuration, reading the image just one time is sufficient evenin the event of outputting multiple copies of the original, so the timerequired for photocopying color originals can be reduced.

[0016] In the event that the image scanner unit 1001 has page memory,the specified original judging is performed during one original scan inparallel with reading of the image. At the point that judgement is madethat there is a specified original image, the image is already stored inthe page memory. Accordingly, in the event that this image is read outof the page memory by some sort of means, this consequently permitsphotocopying of the specified original. Of course, a configuration couldbe made wherein that image output is colored in with a predeterminedvalue at the point that judgement is made that the specified originalexists. However, normally, with configurations having page memory, imagereading and image output are performed asynchronously, so that apparatusmay be out putting an image completely unrelated with this whilescanning the original containing the specified original image. In thiscase, another image output which is not the image to be colored in, willbe colored in.

[0017] Also, an arrangement may be conceived wherein the image stored inthe page memory can be deleted at the point that judgement is made thata specified original image exists. However, with this arrangement, noimage output corresponding to the read image is performed at all, sothere is no record that an unauthorized act was committed, which isundesirable in operating the apparatus.

SUMMARY OF THE INVENTION

[0018] Accordingly, it is an object of the present invention to providean image processing device which solves the above-described problems.

[0019] It is another object of the present invention to provide an imageprocessing device which, with an image processing device having memorywhich stores images to be printed, image signals containing specifiedoriginal images and be suitable processed in the event that originalimages read and stored in memory are output to an image forming device.

[0020] Further objects, features and advantages of the present inventionwill become apparent from the following description of the preferredembodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a diagram describing a configuration example of a colorphotocopier;

[0022]FIG. 2 is a block diagram illustrating a configuration example ofan image processing device according to a first embodiment;

[0023]FIG. 3 is a diagram illustrating an example of an original image;

[0024]FIG. 4 is a diagram describing characteristics determinedaccording to the image areas of image signals obtained by reading anoriginal image;

[0025]FIG. 5 is a diagram describing page management information;

[0026]FIG. 6 is a diagram illustrating synthesized output of multiplepages;

[0027]FIG. 7 is a block diagram illustrating a configuration example ofan output image processing unit;

[0028]FIG. 8 is a diagram illustrating the manner in which a read imageis divided into predetermined sizes;

[0029]FIG. 9 is a diagram illustrating a configuration example of pagemanagement information stored in increments of tiles;

[0030]FIG. 10 is a diagram illustrating an output image example in theevent that tiles making up one page are substituted in a checkeredpattern; and

[0031]FIG. 11 is a block diagram illustrating a configuration example ofan image processing device according to a second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Preferred embodiments of the image processing device according tothe present invention will now be described in detail in accordance withthe accompanying drawings.

[0033] First Embodiment

[0034]FIG. 2 is a block diagram illustrating a configuration example ofan image processing device according to an embodiment.

[0035] [Image Reading]

[0036] A scanner unit 101 reads an original image with a CCD, and sendscolor image signals (RGB image signals) corresponding to the read image,to an input image processing unit 102. The input image processing unit102 subjects the color image signals sent from the scanner unit 101 toknown image processing such as shading correction, CCD line correction,and color correction.

[0037] An image region separation processing unit 103 performs imageregion separation processing of color image signals input from the inputimage processing unit 102. That is to say, this detects characteristicsof the image such as photograph regions, text regions, and halftoneregions, for each of the pixels of the input image, and generates flagdata representing the attributes of each image region.

[0038] [Image Region Separation Processing]

[0039] Image region separation processing is processing for generatingsignals indicating image region attributes by extracting characteristicsof the image (hereafter referred to as “flag data”), in order to performoptimal image processing according to the characteristics of the image.Often, various types of the image regions exist in a mixed manner in theoriginal image, such as full-color photograph regions with continuousgradients, black and white text regions, and halftone print regions suchas with newspaper printing, and so forth. Subjecting these image areasto the same image processing generally will not yield image output ofdesirable image quality. Accordingly, color image signals are used, andimage regions contained in the original image are detected, and flagdata for identifying these is generated.

[0040]FIG. 3 is a diagram illustrating an example of an original image,with a photograph region 202, black text region 203, halftone printregion 204, and color graphics region 205, all existing within a singlepage of the original 201.

[0041] Color image signals obtained by the scanner unit 101 reading thisoriginal image have characteristics determined according to the imageregion. Of the signal values read in each region, plotting the G signalsin the array direction of the CCD yields the curves shown in FIGS. 4Athrough 4D. In FIGS. 4A through 4D, the curves 302, 303, 304, and 305each represent examples of properties manifested characteristically forreading certain lines in the image regions 202 through 205 in FIG. 3.

[0042] Note that the horizontal axis of the graphs shown in FIG. 3represent the pixel positions in the CCD array direction, and thevertical axis represents the signal value, with the vertical axisindicating that the higher the position is, the closer to white (i.e.,bright) the pixel is.

[0043] Describing the characteristics of each image region, at thephotograph region 202, change in signal values according to pixellocation is relatively smooth, and the differences 312 between signalvalues in close proximity exhibit small values. In the black text region203, black characters are drawn owned a white background, so the signalvalues have properties that drastically changed from the whitebackground portion 313 to the character portion of 323. In the halftoneregion 204, the change in signals values has properties wherein brightand dark change is repeated at a high frequency as indicated by thecurve 304 shown in FIG. 4C, since halftone patterns 324 printed on thewhite background are repeated. In the graphics region 205, the signalvalue rapidly becomes smaller at the edge portion 315 of the graphics,while maintaining an approximately constant value within the graphicsportion 316.

[0044] These images regions can be judged by detecting theabove-described characteristics from the image signals, and discerningwhich attributes they correspond to. Accordingly, characteristicsextracting methods using known techniques, such as the accumulation ofvalues of amount of change of signal values near a pixel of interest oramount of change in a predetermined section, luminance values ofsurrounding pixels (whether white or colored backgrounds), the number oflight and dark changes of signal values within a predetermined section,etc., and known attributes judging techniques are used based thereupon.

[0045] Upon image region attributes being detected for each pixel by theabove-described image region separation processing, image processingcorresponding to the image region attributes is executed at a No. 2input image processing unit 104. For example, in the text region, thehigh-frequency component of the image is enhanced in order to increasesharpness of characters, and at the halftone region, so-called low-passfilter processing is performed for eliminating moiré componentscharacteristic of halftone images. Such processing can be switched overin increments of pixels according to the flag data generated by theimage region separation processing unit 103.

[0046] [Accumulation of Image Data]

[0047] The color image signals subjected to the above-described varioustypes of input image processing, and the flag data generated in theabove procedures, are temporarily stored in image memory 105 and flagmemory 106, respectively. At this time, the color image signals and theflag data are stored for an entire page of the original, or apredetermined region portion of one page.

[0048] The temporarily stored color image signals and flag data arecompressed by data compression unit 109 and stored in a storage device110. The storage device 110 is preferably a high-speed storing meanssuch as a semiconductor storage device or the like. Also, the datacompression unit 109 performs a different data compression processingfor the color image signals and the flag data. That is, image data issubjected to data compression processing such as JPEG compression, whichis irreversible, but compresses data with a high compression percentagewithout perceivable deterioration of the image according to human visualproperties. Also, the flag data is subjected to reversible datacompression such as JBIG decompression, so that there is no drop-out orchange in the flag data.

[0049] Thus, the color image signals and flag data that have beensubjected to different compression processing are stored in the storagedevice 110 in increments of pages of the originals. The compressed datastored in the storage device 110 may be written to an auxiliary storagedevice 111. For the auxiliary storage device 111, a medium with a largestorage capacity, such as a hard disk, is suitable, even if therecording speed is somewhat slower. This allows multiple pages of theoriginal images to be effectively stored in the auxiliary storage device111.

[0050] [Specified Original Judging]

[0051] Concurrently with the above image reading, image regionseparation processing, and image data accumulation, the specifiedoriginal judging unit 107 performs specified original judgment. That is,simultaneously with the color image signals subjected to basic imageprocessing at the input image processing device 102 being sent to theimage region separation processing unit 103, these are also sent to thespecified original judging unit 107, judgement is made regarding whetheror not the specified original image such as paper currency or the likethat has been registered beforehand is contained therein, and judgmentsignals 108 indicating the judgement results thereof are generated. Thejudgment signals 108 are sent to the CPU 100 controlling the entireapparatus, and so forth.

[0052] Known technology is used for the specified original judgingmethod, wherein color attributes, 2-dimensional pattern attributes,etc., are extracted from the color image signals sent in time-sequence,the degree of approximation thereof with the color attributes, patternattributes, etc., of specified original image is registered in thememory in the specified original judging unit 107 beforehand (i.e., thedegree of matching) is calculated, and in the event that the degree ofapproximation is at a predetermined value or higher, the judgment signal108 representing that the specified original image exists, is output(e.g., Japanese Patent Laid-Open No. 4-207466, etc.).

[0053] Here, specified original judgment is being performed concurrentlywith the reading and storing of the image, so the specified originaljudgment is completed at the same time that the reading of one page ofthe image of the original is completed. Accordingly, in the event thatthe judgment signal 108 indicating that there is a specified originalimage therein is output, an unshown CPU substitutes substitution imagesignals stored in the storage device 110 or the auxiliary storage device111 beforehand for the image signals that have been judged and stored inthe storage device 110 or the auxiliary storage device 111.

[0054] Substitution image signals are, for example, image signals whichcolor in the entire page black. Compressing such image signalsbeforehand and storing these in the storage device 110 or auxiliarystorage device 111 enables substitution with the image signals havingbeen judged.

[0055] Substitution image signals have a uniform value for the entirepage, so the compressed data size is extremely small, and does not wasteany storage space on the storage device 110 or auxiliary storage device111. Note that the image signals for substitution may be smaller thanthe entire page size. In this case, substitution image signals can berepeatedly output for the entire page.

[0056] Substitution of image signals can be realized by a method whereinthe image signals stored in the storage device 110 or auxiliary storagedevice 111 are first deleted and then over written by the substitutionimage signals.

[0057] Also, as shown in FIG. 5, the image signals can be substituted byrewriting address information indicating the actual storage region ofthe storage device 110 or auxiliary storage device 111 that is writtenin the page management information managing multiple pages of imagesignals written to the storage device 110 or auxiliary storage device111.

[0058] In the event of managing image signals for multiple pages,normally, the CPU 100 stores the page management information for themultiple pages in work memory or the like, as indicated by referencenumerals 401, 402, and 403, in FIG. 5, and holds the actual storageregion location information regarding where the image signals exist, inthe page management information. That is to say, the page managementinformation 401 shown in FIG. 5 stores information indicating the actualstorage region 404 a of the compressed image signals and actualrecording region 404 b of the compressed flag data (leading position).In the same way, the page management information 402 stores informationindicating the actual storage regions 405 a and 405 b of the secondpage, and so forth own through the page management information 403storing information indicating the actual storage regions 406 a and 406b of the N'th page.

[0059] Substitution image signals are stored in an actual storage regiondetermined beforehand, and page management information of pages judgedthat specified original images exist therein are substituted. That is,the page management information is rewritten so as to refer to theactual storage regions 407 a and 407 b where the substitution imagesignals are stored. Note that FIG. 5 illustrates an example whereinjudgment is made that a specified original image exists in the N'thpage, and the page management information 403 of the N'th page issubstituted.

[0060] Further, all flag data for the substitution image signals can beleft at “0”. However, flag data only indicates the attributesinformation for each pixel within the images, so the actual originalimage regarding which duplication is forbidden, cannot be printed outthereby. Accordingly, an arrangement may be made wherein no flag data issubstituted, and only the image signals are substituted. In this case,there is no need to prepare substitution flag data.

[0061] [Reading Out Image Data]

[0062] The compressed image data and attributes flag data stored in thestorage device 110 or auxiliary storage device 111 are read out foroutput to the print unit 117, each expanded at the data expanding unit112, and respectively written to the image memory 114 and flag memory115. At this time, the above-described page management information isreferred to in order to read out the image signals that have beencompressed. Accordingly, with regard to pages that have been judged tocontain specified original images, the above-described substitutionimage signals are read out instead, and stored in the image memory 114.

[0063] A pixel density conversion unit 113 converts the pixel density ofthe image signals that have been read out from the storage device 110 orauxiliary storage device 111, as necessary. This pixel densityconversion unit 113 is used in cases such as enlarging or reducing animage for printing output, or reducing multiple pages of images andsynthesizing the reduced images to make a printer output thereof on onepage.

[0064]FIG. 6 is a diagram illustrating an example of synthesized outputof multiple pages. That is, saying that image signals from reading theimages of two originals 501 and 502 are recorded in the recording device110 beforehand, these are synthesized and printed on a recording sheet503 of the same size as the originals, for example.

[0065] To this end, first, the image signals corresponding to theoriginal 501 are read out from the storage device 110 and expanded,subjected to reduction processing of a predetermined percentage at thepixel density conversion unit 113, and image signals equivalent to theimage 504 subjected to 90 degrees rotation in the counterclockwisedirection at an unshown rotation processing unit are written to apredetermined area in the image memory 114. Next, image signalscorresponding to the original 502 are read out from the storage device110 and expanded, subjected to the same reduction processing, and theimage signals equivalent to the image 505 subjected to rotationprocessing are written to the predetermined area in the image memory114. At this time, the flag data corresponding to the original 501 and502 is also subjected to the expansion, reduction, and rotationprocessing, and written to the corresponding area in the flag memory115.

[0066] Now, it is preferable that different techniques be applied forresolution conversion of the image signals and resolution conversion ofthe flag data. For example, known techniques such as linearinterpolation or bicubic spline interpolation can be used for the imagesignals. Also, for the flag data, resolution conversion methods suitablefor the binary data, such as the nearest-neighbor processing or thelike, is preferably used.

[0067] Due to the above processing, the image 504 and 505 equivalent tothe two originals 501 and 502 are laid out and printed out on the samepage 503, as shown in FIG. 6. However in the event that judgement ismade that a specified original image is contained in, for example, theoriginal 502, substitution image data is read out corresponding to theoriginal 502, so the image that is laid out and printed out onto thesame page as the image 506 equivalent to the original 502 colored inblack, for example, as shown in FIG. 6.

[0068] In this way, images containing specified original images can beinvalidated even in cases for synthesizing and printing out multipleimages. However, in the event that reducing (or enlarging) processing isspecified for the printout, an output image is formed with the originalimage reduced (or enlarged), so that the output printed image has adifferent size as compared to the original regarding which duplicationis forbidden, and consequently, the object of forgery is not effected.Accordingly, a configuration may be conceived wherein theabove-described in the substitution image is not performed in the eventthat an enlargement/reduction percentage of a certain degree (reductionof 70% or less, or enlargement of 140% or more) is specified.

[0069] [Output of Image Data]

[0070] Upon the data amount of the image signals and flag datatemporarily stored in the image memory 114 and flag memory 115 reachinga predetermined amount, the image signals and flag data are sent to anoutput image processing unit 116.

[0071] The output image processing unit 116 performs known imageprocessing for converting the RGB image signals into printing imagesignals, i.e., luminance concentration conversion, masking correction,UCR, gamma correction, quantization (including binarization) processing,etc., and the post-conversion CMYK image signals are output to theprinter unit 117. The printer unit 117 drives the semiconductor laserdevice 1013 based on the CMYK image signals sent thereto, and forms avisible image on the recording paper following the above-describedprocedures.

[0072] The flag data stored in the flag memory 115 is used for switchingover the processing of the output image processing unit 116. That is,the coefficients for masking correction and UCR processing are changedbetween the photograph region and text region, thereby making the outputimage quality suitable. For example, a conversion coefficient whereinpixels are reproduced only with black toner is applied for text regions,i.e., for pixels wherein the text flag is “1”, in other words, acoefficient wherein C, M, and Y are O, is applied for pixels whereinthere is no color. Also, for the regions other than text region,coefficients are applied wherein C, M, and Y, are not O even in theevent that there is no color, so as to reproduce a black with depth.

[0073] Also, quantization processing converts CMYK image signals intobinary signals or the like of “0” and “1” using known error dispersionprocessing or dithering processing. At this time, error dispersionprocessing is applied for text regions and graph regions, since theclarity of the output image has priority, and dithering processing isapplied for photographs and halftone regions, since the gradation haspriority. Thus, the output image quality can be made suitable by aswitching between quantization methods according to the flag data.

[0074]FIG. 7 is a block diagram illustrating a configuration example ofthe output image processing unit 116. The RGB image signals read out ofthe image memory 114 are input in parallel to two RGB/CMYK conversioncircuits 601 and 602, independently subjected to luminance concentrationconversion, masking correction, and UCR, thereby being converted intoCMYK image signals. One output of the RGB/CMYK conversion circuits 601and 602 is selected by a selector 603 following flag data read out ofthe flag memory 115, synchronously with RGB image signals. For example,text region conversion coefficients are set in the RGB/CMYK conversioncircuit 601, and conversion coefficients for regions other than the textregion are set in the RGB/CMYK conversion circuit 602. In the event thatthe flag data is “1”, the selector 603 selects the output of theRGB/CMYK conversion circuit 601, and in the event that the flag data is“0”, the selector 603 selects the output of the RGB/CMYK conversioncircuit 602.

[0075] The output of the selector 603 is applied in parallel to a systemof a gamma correction circuit 604 and error dispersion processing unit606, and a system of a gamma correction circuit 605 and ditheringprocessing unit 607. A selector 608 selects one of the output of bothsystems, which is sent to the printer unit 117. In the event that errordispersion processing is to be applied for the text region and graphregion, the output of the error dispersion processing circuit 606 isselected in the event that the text flag is “1” or the shape flag is“1”, and otherwise, the output of the dithering processing circuit 607is selected.

[0076] Modifications

[0077] With the above-described embodiment, an example has beendescribed wherein image signals containing specified original images aresubstituted with image signals which color in the entire page black, butthe present invention is by no means restricted this, and may besubstituted with image signals which color in the page with white or aspecified color, or image signals which print a warning text which warnsof illegal activity.

[0078] Also, an arrangement may be made wherein the image is not coloredin, but flag data is substituted. In this case, flag data wherein theattributes of the entire page (text attributes, halftone attributes,etc.,) are all set to “1” is created, compressed, and stored in thestorage device 110 or the like, as substitution flag data. In the eventthat an image is judged to contain a specified original image, the flagdata of the problem page is substituted with the above-described flagdata. At the time of printing out the page, the table of one of theRGB/CMYK conversion circuits shown in FIG. 7 (e.g., RGB/CMYK conversioncircuit 602) is rewritten so as to constantly output black image signalsregardless of the input image signals, and in the event that the valueof flag data is all “1”, the output of the RGB/CMYK conversion circuit602 is selected. Thus, an image wherein the entire page is colored inblack is output by substituting the flag data, without substituting theimage signals.

[0079] Also, a configuration has been described wherein both the imagesignals and flag data are stored, but it is needless to say that thereare cases wherein the flag data does not need to be stored in thestorage device 110 or the like, and the above-described embodiment mayalso be applied to methods wherein only the image signals are stored.

[0080] Also, with the above embodiments, it is not essential to storesubstitution image signals equivalent to an image of the same size asthe read image, in the storage device 110 or the like. The storageregion for keeping the substitution image signals can be conserved byusing an image which is far smaller than the read image size. Forexample, let us say that that output size of the image represented bythe substitution image signals is 5 cm×5 cm. In the event that judgementis made that the specified original image is contained, the substitutionimage signals are repeatedly read out and continuously printed out, thusenabling the entire page to be colored in black.

[0081] Also, compressing the substitution image signals and flag dataallows the resources of the storage device 110 to be effectively used.At this time, other compression methods including non-compression may beemployed, besides the above-described compression methods.

[0082] With the above-described embodiment, description has been madewherein the image signals of the read image and the substitution imagesignals are handled in increments of pages. However, a configuration canbe made wherein the image signals are divided into partial regions andstored, and image signals are substituted in increments of partialregions.

[0083]FIG. 8 is a diagram illustrating dividing a read image intopredetermined sizes. Image signals for one page are divided intorectangular regions of Nx pixels horizontally and Ny pixels vertically,the image is compressed in increments of the rectangular regions(hereafter referred to as “tiles”), so that the first tile 701, secondtile 702, third tile 703, and so forth are sequentially stored in thestorage device 110, up through the last tile 704. In the event ofoutputting the stored image signals, the compressed tiles are read outand expanded based on the stored order, reconstructed into raster data,and output to the printer unit 117 in increments of lines.

[0084]FIG. 9 is a diagram illustrating the configuration example of pagemanagement information stored in increments of tiles. Is generally thesame as that shown in FIG. 5, but has a data management configuration inincrements of titles instead of management in increments of pages asshown in FIG. 5. That is, the header information 801 of the first tilestores the location (position) information of the actual storage region804 a where the compressed image data of the first tile and the location(position) information of 804 b where the compressed flag data of thefirst tile are stored, the header information 802 of the second tilestores the location (position) information of the actual storage region805 a where the compressed image data of the second tile and thelocation (position) information of 805 b where the compressed flag dataof the second tile are stored, and so forth, so that the headerinformation of all of the tiles making up one page through the headerinformation 803 of the last tile, is stored as one set of pagemanagement information. The substitution image data and flag data arestored in the actual storage regions 807 a and 807 b beforehand.

[0085] In the event that judgement is made that a specified originalimage is contained, the location information held by the headerinformation of all tiles is rewritten so as to point to the actualstorage regions 807 a and 807 b storing the substitution image data.Thus, the image data corresponding to all titles is substituted withsubstitution image data, and image signals read out from the storagedevice 110 and the like and sent to the printer unit 117 are signalswherein the entire page is colored in black, or the like.

[0086] Now, the amount of the substitution image data and flag data is adata amount equivalent to a tile size far smaller than the entire page,and accordingly can be kept from hoarding storage area in the storagedevice 110 or the like.

[0087] Also, replacing with substitution image data does not need to beapplied for all tiles, and may be carried out every other tile, forexample. FIG. 10 is a diagram illustrating an output image example inthe case of substituting the header information for corresponding tilesmaking up one page, so that substitution is carried out in a checkeredpattern. This allows tiles to be colored in black while leaving acertain amount of the original information, which is effective inidentifying what sort of specified a original was contained in the imagethat had been read. This is also effective in reducing consumption ofcoloring agent such as toner or the like.

[0088] According to the above-described embodiment, with an imageprocessing device wherein image data read by scanning in original imageis temporarily stored in output, in the event that judgement is madethat the specified original image is contained, true reproduction of theoriginal image is inhibited and unauthorized duplication is preventedbeforehand, while allowing an image indicating the unauthorized activityto be printed out. Accordingly, the unauthorized activity can be broughtto the attention of the individual attempting the unauthorizedduplication, thereby effectively suppressing such unauthorized activity.

[0089] Second Embodiment

[0090] With the above-described embodiment, a case has been describedwherein input image data is supplied from an image input device fordigitally reading original images, but the image input means of thepresent invention are not restricted to such. With the secondembodiment, a case will be described wherein data is printed out from acomputer.

[0091]FIG. 11 is a block diagram illustrating an example of aconfiguration carrying out the present invention, in the case of aconfiguration wherein electronic document images created on a computerare printed out.

[0092] [Communication Interface Unit and Raster Data Generating Unit]

[0093] Document data to be printed is generally created with a certainapplication on an unshown personal computer.

[0094] The created document data is sent out onto a communication path1119 such as a network as PDL data, via a printer driver within thecomputer.

[0095] Now, PDL is short for Page Description Language, and refers to alanguage system for describing the image of an entire page as a commandformat stipulated by components making up a document image. Well-knowndescription language systems include PostScript (a registered trademark)LIPS (a registered trademark), PCL (a registered trademark), and soforth.

[0096] The PDL data that is sent out is received by a communicationinterface 1105 and temporarily stored in a auxiliary storage device 1104such as a hard disk.

[0097] Upon completion of reception of one page of PDL data, a CPU 1000transfers the received PDL data to a PDL interpreter unit 1101. The PDLinterpreter converts the PDL commands described in a particular languageinto intermediate language data not dependent on the type of PDLlanguage. Thus, the subsequent processing can be standardized regardlessof what sort of description language the input PDL data is describedwith.

[0098] Next, the generated intermediate language data is converted intoa display list for driving a subsequent RIP unit 1103, at a display listgenerating unit 1102. The RIP unit 1103 converts the display list into araster image. RIP stands for Raster Image Processor, and has functionsfor generating image data as a collection of pixels as described withthe first embodiment, in increments of rasters (lines), based on theinput display list.

[0099] Normally, PDL data and intermediate language data are configuredin increments of components making up the document, so there is the needto order the components so as to line up in increments of lines from thetop of the page, in order to generate raster data at the RIP unit. Thedisplay list is the intermediate language data which is rearranged inthe order of the components from the top of the page.

[0100] Following RIP processing, the raster data is 2-dimensional pixelarrayed data wherein color signals of the three colors R, G, and B, arearrayed in point sequence, in the same way as the image read by ascanner.

[0101] Also, an arrangement may be conceived wherein such RIP processingis performed on the computer creating the document data instead of theprinter, and in such a case, the raster image data would be receivedfrom the communication interface unit 1105, temporarily stored in theauxiliary storage device 1104, and then handled as being equivalent tothe output of the RIP unit 1103.

[0102] [Generating Attributes Flag Data]

[0103] With the RIP unit 1103, attributes flag data indicating thatattributes of the image in increments of pixels can be generated at thesame time as generating the raster image data.

[0104] As described with the first embodiment, the attributes flag datais used for subjecting each pixel of the document image to be output tooptimal image processing, according to the characteristics thereof.

[0105] For example, a PDL document contains various types of imageregions together, such as full-color photograph images with continuousgradation, text regions of black alone, lines and curves called vectorobjects, regions represented by shapes, and so forth.

[0106] As with the first embodiment, subjecting these image areas to thesame image processing generally will not yield image output of desirableimage quality.

[0107] The RIP unit 1103 shown in FIG. 11 generates attributes flag databased on one attributes information added to the input display list. Forexample, with regard to a part (object) input as text with the PDLcommand, information indicating text attributes is also provided on thedisplay list, and a text flag is set for the attributes flag informationcorresponding to the pixels generated as text, at the time of renderingthis display list as a raster image.

[0108] In the same way, photograph flags are set for photograph partregions, and vector flags are set for the vector object part regions.

[0109] Accordingly, the attributes flag information thus generated isreflected in the latter-described output image processing, so optimalimage processing can be performed on each of the parts.

[0110] [Accumulation of Image Data]

[0111] The raster image data rendered at the RIP unit 1103, and theattributes flag data generated in the above procedures, are temporarilystored in first image memory 1111 and first flag memory 1106,respectively. At this time, the image data and the attributes flag dataare stored for an entire page of the original, or a region portion ofone page of a predetermined size.

[0112] The image data and attributes flag data are of a data format thesame as that in the first embodiment, so subsequent processing isapproximately the same as that in the first embodiment.

[0113] The temporarily stored image data and attributes flag data arecompressed by a data compression unit 1109 and stored in a storagedevice 1110. The storage device 1110 is preferably a high-speed storingmeans such as a semiconductor storage device or the like. Also, the datacompression unit 1109 performs a different data compression processingfor the image data and attributes flag data. That is, image data issubjected to data compression processing such as JPEG compression, whichis irreversible, but compresses data with a high compression percentagewithout perceivable deterioration of the image according to human visualproperties, and the flag data preferably is subjected to reversible datacompression such as JBIG decompression, so that there is no drop-out orchange in the flag data.

[0114] Thus, the image data and flag data that have been subjected todifferent compression processing are stored in the storage device 1110in increments of pages of the originals.

[0115] [Specified Original Judging Unit]

[0116] Concurrently with the above raster image generating andattributes flag generating processing, the specified original judgingunit 1107 performs judgment regarding whether or not specified originalimages are contained in the raster image signals.

[0117] That is, simultaneously with the raster image data being sent tothe first image memory (1111), this is also sent to the specifiedoriginal judging unit 1107, judgement is made regarding whether or notan image regarding which reproduction is forbidden that has beenregistered beforehand is contained therein, judgment signals 1108indicating the judgement results thereof are generated, and notified toan unshown CPU or the like.

[0118] As with the first embodiment, known technology can be used forthe specified original judging method, wherein color attributes,2-dimensional pattern attributes, etc., are extracted from the colorimage signals sent in time-sequence, the degree of approximation thereofwith the color attributes, pattern attributes, etc., of specifiedoriginal image is registered in the memory in the specified originaljudging unit 1107 beforehand (i.e., the degree of matching) iscalculated, and in the event that the degree of approximation is at apredetermined value or higher, judgment results to the effect that aspecified original image exists are output, while in the event that thedegree of approximation is at a predetermined value or lower, judgmentresults to the effect that a specified original image does not exist areoutput.

[0119] Also, in this case, a processing method may be applied whereinand judgment of presence of specified originals is performed whilemaking reference to the attributes flag information. In creating data ona computer as a PDL document, unauthorized image contained therein areoften specified original image data such as paper currency of the like,read in with commercially-available flat-head scanner or the like. Insuch cases, “photograph” attributes are provided to the image attributesfor the part of the specified original image. Accordingly, the specifiedoriginal judging unit 1107 can make reference to the attributes flaginformation transferred from the RIP unit 1103, and makes the judgingprocessing valid only in the event that a “photograph flag” is attachedto the image data being judged.

[0120] Thus, erroneously judging the existence of a specified originalby performing the judging processing for regions other than thephotograph regions where unauthorized images exist, can be prevented.

[0121] Now, the specified original judgment processing and the rasterimage generation and storing are executed consecutively, meaning thatpresence or absence of a specified original is detected at the same timethat the raster image generation is completed.

[0122] Accordingly, in the event that there is judgment that a specifiedoriginal exists, the CPU 1000 instructs that the problem image datastored in the storage device 1110 be replaced with the second image datastored in the storage device 1110 beforehand.

[0123] The second image data here is image data wherein the entire pagehas been colored black (R=G=B=0). This can replace the data on theproblem page that has been read in and stored, by being subjected toJPEG compression and stored in the storage device 1110 beforehand. Thedata size of the second image data is extremely small following JPEGcompression, since the data has a uniform value for the entire page, andaccordingly does not waste great amounts of space in the storage area.

[0124] The substitution processing performed here is the same as themethod described in the first embodiment with reference to FIG. 4, sosubsequent description will be omitted.

[0125] [Reading Out Image Data]

[0126] The compressed image data and attributes flag data stored in thestorage device 1110 are read out for printing to the print unit 1117,each expanded at the data expanding unit 1112, and respectively writtento the second image memory 1114 and second flag memory 1115.

[0127] At this time, the image data location information is saved in thepage information described in the first embodiment is referred to inorder to read out the actual image data. Accordingly, with regard topages that have been judged to contain specified original images, theblack image data is read out instead, and stored in the second imagememory 1114.

[0128] Also, as with the first embodiment, the density conversion unit1113 converts the pixel density of the image signals that have been readout from the storage device 1110, as necessary.

[0129] [Output of Image Data]

[0130] Upon the data amount of the image signals and flag datatemporarily stored in the second image memory 1114 and second flagmemory 1115 reaching a predetermined amount, the image signals and flagdata are sent to an output image processing unit 1116.

[0131] The output image processing unit 1116 performs known imageprocessing for converting the RGB image signals into printing imagesignals, i.e., luminance concentration conversion, RGB/CMYK conversion,binarization processing, etc., and the post-conversion CMYK imagesignals are output to the printer unit 1117. The printer unit 1117performs laser driving based on the CMYK image signals sent thereto, andforms a visible image on the recording paper following the sameprocedures as those in the first embodiment.

[0132] The flag data stored in the second flag memory 1115 is used forswitching over the processing of the output image processing unit 1116.That is, the coefficients for masking correction and RGB/CMYK conversionare changed between the photograph region and text region, therebyimproving the output image quality. For example, a conversioncoefficient wherein pixels are reproduced only with black toner isapplied for text regions, i.e., for pixels wherein the text flag is “1”,(in other words, a coefficient wherein C, M, and Y are 0), is appliedfor pixels wherein there is no color, and for the regions other thantext region, coefficients are applied wherein C, M, and Y, are not 0even in the event that there is no color, so as to reproduce a blackwith depth.

[0133] Also, binarization processing converts CMYK image signals intobinary signals or the like of “0” and “1” using known error dispersionprocessing or dithering processing, and at this time, applying errordispersion processing for text regions and graph regions since theclarity of the output image has priority, and applying ditheringprocessing for photographs and halftone regions since the gradation haspriority, so as to execute binarization processing in the same manner aswith the first embodiment, improves the output image quality byswitching between quantization methods according to the flag data.

[0134] However, the configurations of the attribute flags are somewhatdifferent, so the degree of freedom differs somewhat in the selectionmethod for selecting, for example, the error dispersion processing forregions wherein the text flag or vector flag is 1.

[0135] Also, as described in the first embodiment, an arrangement may bemade wherein the image is compressed in increments of tiles at the datacompression unit 1109, and the substitution image is also substituted inincrements of tiles. The specific processing thereof is the same as thatof the first embodiment, and accordingly description thereof will beomitted.

[0136] Note that the present embodiment may be applied to a systemconfigured of multiple devices (e.g., host computer, interface device,reader printer, etc.), or to a stand-alone device (e.g., a photocopier,facsimile device, etc.).

[0137] Also, it is needless to say that the objects of the presentinvention can be achieved by an arrangement wherein a storing medium (orrecording medium) storing software program code for realizing thefunctions of the above embodiments is supplied to a system or device,and the program code stored in the storing medium is read out andexecuted by the computer (or CPU or MPU) of the system or device. Inthis case, the program code itself read out from the storing mediumrealizes the functions of the above-described embodiments, and thestoring medium storing the program code comprises the present invention.Also, it is needless to say that the present invention encompasses casesnot only where the computer executing the program code read out realizesthe functions of the above embodiments, but also where the operatingsystem or the like running on the computer executes part or all of theactual processing based on the instructions of the program code, therebyrealizing the functions of the above-described embodiments.

[0138] Further, it is needless to say that the scope of the presentinvention also encompasses arrangements wherein the program code readout from the storing medium is written to memory provided to functionexpansion boards inserted into the computer or function expansion unitsconnected to the computer, following which a CPU or the like provided tothe function expansion board or function expansion unit performs all orpart of the actual processing based on instructions of the program code,so as to realize the functions of the above-described embodimentsthereby.

[0139] In the event that the present invention is applied to anabove-described storing medium, the storing medium stores program codecorresponding the above-described flowcharts.

[0140] While the present invention has been described with reference towhat are presently considered to be the preferred embodiments, it is tobe understood that the invention is not limited to the disclosedembodiments. On the contrary, the invention is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims. The scope of the following claims is to beaccorded the broadest interpretation so as to encompass all suchmodifications and equivalent structures and functions.

What is claimed is:
 1. An image processing device comprising: a readingunit arranged to read an original image; first memory arranged to storea plurality of pages of images read by said reading unit; second memoryarranged to store images to print from the images stored in said firstmemory; third memory arranged to store substitution images; a printeroutput unit arranged to output images stored in said second memory to aprinter; a judging unit arranged to judge whether or not specifiedoriginal images are contained in the images read by said reading unit;and a control unit arranged to store in said second memory asubstitution image stored in said third memory, instead of an image of apage judged to contain said specified original image.
 2. An imageprocessing device according to claim 1, wherein said control unitrepeatedly reads out the substitution image stored in said third memory,and stores in said second memory.
 3. An image processing deviceaccording to claim 1, further comprising: a data compression unitarranged to compress images; and a data expansion unit arranged toexpand compressed images; wherein said first memory stores compressedimages, and said second memory stores expanded images.
 4. An imageprocessing device comprising: a reading unit arranged to read anoriginal image; first memory arranged to store a plurality of pages ofimages read by said reading unit; second memory arranged to store imagesto print from the images stored in said first memory; third memoryarranged to store substitution images; a control unit arranged to managemanagement information indicating the storage location of images of eachpage stored in said first memory; a printer output unit arranged tooutput images stored in said second memory to a printer; and a judgingunit arranged to judge whether or not specified original images arecontained in the images read by said reading unit; wherein said controlunit rewrites management information of pages judged by said judgingunit to contain specified original images, so as to be correlated to thesubstitution images stored in said third memory.
 5. An image processingdevice according to claim 4, wherein said control unit performs managingso as to repeatedly read out the substitution image stored in said thirdmemory.
 6. An image processing device according to claim 4, furthercomprising: a data compression unit arranged to compress images; and adata expansion arranged to expand images; wherein said first memorystores compressed images, and said second memory stores expanded images.7. An image processing device comprising: a reading unit arranged toread an original image; a compression unit arranged to divide one pageof images read by said reading unit into a plurality of block regions ofa predetermined size and to compress each block region; first memoryarranged to store images of the block regions compressed by saidcompression unit; an expansion unit arranged to expand images of theblock regions stored in said first memory; second memory arranged tostore images expanded by said expansion unit; third memory arranged tostore substitution images; a printer output unit arranged to outputimages stored in said second memory to a printer; a judging unitarranged to judge whether or not specified original images are containedin the images read by said reading unit; and a control unit arranged tostore in said second memory a substitution image stored in said thirdmemory, instead of images of the block regions stored in said firstmemory, in the event that judgment is made by said judging unit tocontain said specified original image.
 8. An image processing deviceaccording to claim 7, wherein said control unit stores in said secondmemory a substitution image stored in said third memory instead of apart of the block regions out of the block regions of one page stored insaid first memory.
 9. An image processing device comprising: a readingunit arranged to read an original image; a compression unit arranged todivide one page of images read by said reading unit into a plurality ofblock regions of a predetermined size and to compress each block region;first memory arranged to store images of the block regions compressed bysaid compression unit; an expansion unit arranged to expand images ofthe block regions stored in said first memory; second memory arranged tostore images expanded by said expansion unit; third memory arranged tostore substitution images; a control unit arranged to manage managementinformation indicating the storage location of images of each blockregion stored in said first memory; a printer output unit arranged tooutput images stored in said second memory to a printer; and a judgingunit arranged to judge whether or not specified original images arecontained in the images read by said reading unit; wherein said controlunit rewrites management information of each block region in the eventthat judgment is made by said judging unit to contain specified originalimages, so as to be correlated to the substitution images stored in saidthird memory.
 10. A control method for an image processing device,comprising: a reading step arranged to read an original image; a firststoring step arranged to store a plurality of pages of images read insaid reading step in first memory; a second storing step arranged tostore images to print from the images stored in said first memory, insecond memory; a third storing step arranged to store substitutionimages in third memory; an output step arranged to output images storedin said second memory to a printer; a judging step arranged to judgewhether or not specified original images are contained in the imagesread in said reading step; and a substituting step arranged to store insaid second memory a substitution image stored in said third memory,instead of an image of a page judged to contain said specified originalimage.
 11. A control method for an image processing device, comprising:a reading step arranged to read an original image; a first storing steparranged to store a plurality of pages of images read in said readingstep in first memory; a managing step arranged to manage managementinformation indicating the storage location of images of each pagestored in said first memory; a second storing step arranged to storeimages to print from the images stored in said first memory, in secondmemory; an output step arranged to output images stored in said secondmemory to a printer; a judging step arranged to judge whether or notspecified original images are contained in the images read in saidreading step; and a rewriting step arranged to rewrite managementinformation of pages judged in said judging step to contain specifiedoriginal images, so as to be correlated to the substitution imagesstored in said third memory.
 12. A control method for an imageprocessing device, comprising: a reading step arranged to read anoriginal image; a compression step arranged to divide one page of imagesread in said reading step into a plurality of block regions of apredetermined size and to compress each block region; first storing steparranged to store images of the block regions compressed in saidcompression step in first memory; an expansion step arranged to expandimages of the block regions stored in said first memory; a secondstoring step arranged to store images expanded in said expansion step insecond memory; an output step arranged to output images stored in saidsecond memory to a printer; a judging step arranged to judge whether ornot specified original images are contained in the images read in saidreading step; and a substituting step arranged to store in said secondmemory a substitution image stored in third memory, instead of images ofthe block regions stored in said first memory, in the event thatjudgment is made in said judging step to contain said specified originalimage.
 13. A control method for an image processing device, comprising:a reading step arranged to read an original image; a compression steparranged to divide one page of images read in said reading step into aplurality of block regions of a predetermined size and to compress eachblock region; a first storing step arranged to store images of the blockregions compressed in said compression step in first memory; a managingstep arranged to manage management information indicating the storagelocation of images of each block region stored in said first memory; anexpansion step arranged to expand images of the block regions stored insaid first memory; a second storing step arranged to store imagesexpanded in said expansion step in second memory; an output steparranged to output images stored in said second memory to a printer; ajudging step arranged to judge whether or not specified original imagesare contained in the images read in said reading step; and a rewritingstep arranged to rewrite management information of the block regions, inthe event that judgment is made in said judging step to contain saidspecified original image, so as to be correlated with the substitutionimages stored in said third memory.
 14. An image processing device,comprising: a receiving unit arranged to receive print data from anexternal computer; a rendering unit arranged to render print datareceived by said receiving unit as an image; first memory arranged tostore a plurality of pages of images rendered at said rendering unit;second memory arranged to store an image for printing from images storedin said first memory; third memory arranged to store substitutionimages; a printer output unit arranged to output images stored in saidsecond memory to a printer; a judging unit arranged to judge whether ornot specified original images are contained in the images rendered bysaid rendering unit; and a control unit arranged to store in said secondmemory a substitution image stored in said third memory, instead of animage of a page judged to contain said specified original image.
 15. Animage processing device, comprising: a receiving unit arranged toreceive print data from an external computer; a rendering unit arrangedto render print data received by said receiving unit as an image; firstmemory arranged to store a plurality of pages of images rendered at saidrendering unit; second memory arranged to store an image for printingfrom images stored in said first memory; third memory arranged to storesubstitution images; a control unit arranged to manage managementinformation indicating the storage location of images of each pagestored in said first memory; a printer output unit arranged to outputimages stored in said second memory to a printer; and a judging unitarranged to judge whether or not specified original images are containedin the images rendered by said rendering unit; wherein said control unitrewrites management information of pages judged by said judging unit tocontain specified original images, so as to be correlated to thesubstitution images stored in said third memory.
 16. An image processingdevice, comprising: a receiving unit arranged to receive print data froman external computer; a rendering unit arranged to render print datareceived by said receiving unit as an image; a compression unit arrangedto divide one page of images rendered by said rendering unit into aplurality of block regions of a predetermined size and to compress eachblock region; first memory arranged to store images of the block regionscompressed by said compression unit; an expansion unit arranged toexpand images of the block regions stored in said first memory; secondmemory arranged to store images expanded by said expansion unit; thirdmemory arranged to store substitution images; a printer output unitarranged to output images stored in said second memory to a printer; ajudging unit arranged to judge whether or not specified original imagesare contained in the images rendered by said rendering unit; a controlunit arranged to store in said second memory a substitution image storedin said third memory, instead of images of the block regions stored insaid first memory, in the event that judgment is made by said judgingunit to contain said specified original image.
 17. An image processingdevice, comprising: a receiving unit arranged to receive print data froman external computer; a rendering unit arranged to render print datareceived by said receiving unit as an image; a compression unit arrangedto divide one page of images rendered by said rendering unit into aplurality of block regions of a predetermined size and to compress eachblock region; first memory arranged to store images of the block regionscompressed by said compression unit; an expansion unit arranged toexpand images of the block regions stored in said first memory; secondmemory arranged to store images expanded by said expansion unit; thirdmemory arranged to store substitution images; a control unit arranged tomanage management information indicating the storage location of imagesof each block region stored in said first memory; a printer output unitarranged to output images stored in said second memory to a printer; anda judging unit arranged to judge whether or not specified originalimages are contained in the images rendered by said rendering unit;wherein said control unit rewrites management information of blockregions in the event that judgment is made by said judging unit tocontain specified original images, so as to be correlated to thesubstitution images stored in said third memory.
 18. A control methodfor an image processing device, comprising: a receiving step arranged toreceive print data from an external computer; a rendering step arrangedto render print data received in said receiving step as an image; afirst storing step arranged to store in first memory a plurality ofpages of images rendered in said rendering step; a second storing steparranged to store in said second memory an image for printing fromimages stored in said first memory; a third storing step arranged tostore substitution images in third memory; an output step arranged tooutput images stored in said second memory to a printer; a judging steparranged to judge whether or not specified original images are containedin the images rendered in said rendering step; and a substituting steparranged to store in said second memory a substitution image stored insaid third memory, instead of an image of a page judged to contain saidspecified original image.
 19. A control method for an image processingdevice, comprising: a receiving step arranged to receive print data froman external computer; a rendering step arranged to render print datareceived in said receiving step as an image; a first storing steparranged to store in first memory a plurality of pages of imagesrendered in said rendering step; a managing step arranged to managemanagement information indicating storage location of each page ofimages stored in said first memory; a second storing step arranged tostore in second memory an image for printing from images stored in saidfirst memory; an output step arranged to output images stored in saidsecond memory to a printer; and a judging step arranged to judge whetheror not specified original images are contained in the images rendered insaid rendering step; a rewriting step arranged to rewrite managementinformation of pages judged in said judging step to contain saidspecified original image, so as to be correlated with the substitutionimages stored in said third memory.
 20. A control method for an imageprocessing device, comprising: a receiving step arranged to receiveprint data from an external computer; a rendering step arranged torender print data received in said receiving step as an image; acompression step arranged to divide one page of images rendered in saidrendering step into a plurality of block regions of a predetermined sizeand to compress each block region; a first storing step arranged tostore in first memory images of the block regions compressed in saidcompression step; an expansion step arranged to expand images of theblock regions stored in said first memory; a second storing steparranged to store in said second images expanded in said expansion step;an output step arranged to output images stored in said second memory toa printer; a judging step arranged to judge whether or not specifiedoriginal images are contained in the images rendered in said renderingstep; a substituting step arranged to store in said second memory asubstitution image stored in third memory, instead of images of theblock regions stored in said first memory, in the event that judgment ismade in said judging step to contain said specified original image. 21.A control method for an image processing device, comprising: a receivingstep arranged to receive print data from an external computer; arendering step arranged to render print data received in said receivingstep as an image; a compression step arranged to divide one page ofimages rendered in said rendering step into a plurality of block regionsof a predetermined size and to compress each block region; a firststoring step arranged to store in first memory images of the blockregions compressed in said compression step; a managing step arranged tomanage management information indicating storage location of images ofthe block regions stored in said first memory; an expansion steparranged to expand images of the block regions stored in said firstmemory; a second storing step arranged to store in second memory imagesexpanded in said expansion step; an output step arranged to outputimages stored in said second memory to a printer; a judging steparranged to judge whether or not specified original images are containedin the images rendered in said rendering step; and a rewriting step forrewriting management information of the block regions so as to becorrelated to the substitution images stored in third memory, in theevent that judgment is made in said judging step to contain specifiedoriginal images.